If you're careful and are able to remove the trackpad connector without damage, it is possible to lean the top case and metal shield against the screen, without having to remove the speaker and power connectors, while you replace the hard drive. You'll have to unstick the speaker cable from the shield first, remove the screws, and reroute the speaker cable out of the notch that it's in. SLOWLY remove the metal shield and CAREFULLY lean it up against the screen.

Follow crtolson's advice, but when prying the connectors, do it one side at a time, and use a LIGHT touch when doing so. Work each side slowly, HOLDING DOWN THE HEADER IN THE CENTER WITH A SMALL FLAT-HEAD PRECISION SCREWDRIVER, pulling up lightly with the spudger once per side. The connector will eventually come loose enough to lift it from the header. DO NOT USE YOUR FINGERS! Always use a spudger.

The instructions in CAPS are VERY important, lest you pull the header off the board. I've made this mistake myself, and I've been working on Mac notebooks for 20 years...